Wire grid polarizers (WGP) have been not only used in polarizing optical systems but also effectively applied as beam splitters as well, particularly in liquid crystal based microdisplay projection applications. Such a beam splitter operates in a fairly wide visible spectrum which reflects one linear polarization and transmits the other, with considerable high contrast and optical efficiency among other advantages
Polarizing wire grids are disposed on an outer surface of an optical transparent substrate, such as glass. A conventional wire grid polarizer basically consists of elongated but spaced-apart wire grids, made of a reflective metal such as aluminum in a nanometer scale, in a parallel array adherent to a flat glass panel as disclosed by Hansen in U.S. Pat. No. 6,243,199. Obviously, this configuration is very fragile under challenging assembly and application conditions in which physical and chemical damages could easily occur on those fine scale metal grids. Various modifications in a variety of physical configurations based on the conventional configuration of a thin plate are made to improve robustness while maintaining or enhancing optical performance of polarization and beam splitting functions as designed.
FIG. 1a is a schematic view of a conventional wire grid polarizing panel 10 in prior art. The configuration of such a wire grid polarizing panel 10 includes an array of elongated reflective elements 2 laid onto a glass plate 1, which is fairly fragile to any external damage during fabrication and handling. FIG. 1b illustrates a simple optical engine 5 for projection display, employing a wire grid polarizing panel 10 associated with a reflective imager 90 and a light source 95. The wire grid polarizing panel 10 reflects incident illumination in one polarization state, P, which illuminates the reflective imager 90 for projection display formation, and let pass the other, S.
Even in such simple configuration, need becomes obvious for improvement in the system integration and robustness of the optical engine 5 and its core components, the wire grid polarizing panel 10 and the reflective imager 90. It is highly desirable that those two critical components, the wire grid polarizing panel 10 and the reflective imager 90, are better physically integrated and aligned, while optical distinction between them is minimized.